Fig. 6. In the absence of extrinsic cues, neuroblast cortical polarity does not form until metaphase. (A-D) Double-labeled clustered and (E-H) isolated neuroblasts in culture, fixed and stained for aPKC and PH3 (top row), and for -tubulin (bottom row). Mitotic stages are listed above each panel. White arrowheads indicate the center of the aPKC crescent. Scale bar: 5 µm.